Process of producing flax felt.



A PA 7 orrrcn.

TJ'AMES 1. menu; or LE BOYQNIINNESOTA, ASSIGNOB, BY MESNE ASSIGNMENTS, To

NORTHERN INSULATING COMPANY, OF ST. PAUL, MINNESOTA, A CORPORATION OF I MINNESOTA. w i

. PROCESS OF PRODUCING FLAX FELT.

1,125,347, I Specification of Letters Patent.

.80 Drawing.-

' To all whom it may concern:

Be it known that 1, JAMES E. LArrEN, a citizen of the United States, residing at Le Boy, in the county of Mower and State of Minnesota, have invented certain new and useful'Improvements in Processes of. Prov the present invention consists in the novel.

ducing Flax Felt; and I do hereby declare "the following to be a full, clear, and exact method or process for producingsuch flax felt, and which novel process is hereinafter set forth and defined in the claim.

As is well known by all persons familiar with this art, the stemof the flax p'lant'is composed of an inner tube of wood, or woody' tissue, commonly called shive, the

" long or bast fiber directly outward of the wood or-shive and an outermpst skin, ordinarily called the cortical tissue. It is also well known that this body of bast fiber is composed of bundles of filaments and these filaments, in turn are composed of the ultimate fibers which are hollow.- The shive, or woody tissue, is also composed of ultimate fibers which are hollow, but the ultimate fibers of'the shive are relatively short as compared with the ultimate fibers of the bast. The bast fibers are many times longer than the shive. It is also well known that the "bast and the cortical tissue contain gummy materials which, when exposed to moisture and heat, will cause the mass of material containing the same to ferment. It is equally well known that caged or noncirculating dead air is a good non-conductor of heat. It is not as good as a vacuum, but, if the; air is confined in small cells so that circulation and convection cannot take place, it is perhaps the next best heat insulator to any commercially available vacuum.

The flax felt disclosed and claimed in my said Patent, 908,681, utilizes the above stated principles to perhaps the greatest possible v advantage; or, otherwise and briefly stated,

it is a self sustaining material composed of the long, hollow fibers of the bast,,and the Application filed August 13, 1906. Serial No. 830,274.

grades thereof can b comparatively short fibers of the shive from which SllfllClGIlt of ,the gum has been removed tot prevent the fermentation thereof and which are afterward felted together into a .sheet and then compressed and dried,thereby rendering available the hollow fibers of the bast and the shive for the encagement of a r therein, and also encaging great quantit1es of an in the spaces or interstices be tweenthe felted fibers. This product is produced preferably from flax tow, but coarse from the flax straw, as t e same comes from an ordinary threshing machine. ter, however, to first run the threshed straw through an ordinary tow machineso as to knock off more or less of the shive and thereby get what is commercially known as upholstering tow, or a product which is a little more than half bast fiber and a little less than half shive. When in this condition, the shive in the tow will be in broken and splintered form, chiefly adherent to the bust;

but there will be some shive entirely detached from the best, but held tangled up therewith to a greater or less extent, and there will be some of the bast which is entirely free from shive.

Whether the flax straw, itself, or the flax tow be used as the starting point,

the processoftreatment to get the above noted product, is as follows The flax straw '01" tow is first cooked in a suitable didistributed and into interlacing or felting relations in respect to each other while they are held in suspension in the water. The cooked material, as it comes from the digester, is in bunches or lumpy tangled masses of various. sizes utterly incapable, without further treatment, of being felted together into a sheet of uniform thickness and texture. It has been customary to grind up such cooked stock by treating the same in a beating en ine until the stock was brought into the orm of pulp and then to use this pulp in the customary produced directly It is betway for the manufacture of paper, but such a product is unsuitable for heat insulating purposes. Idiscovered that, by the proper treatment of the said bunches or masses of long-fiber stock cooked in a chemical solution, as above stated, the said bunchesor masses could be torn apart and their fibrous elements separated and that, by properly manipulating the same in water, said fibrous elementscould be re-arranged and re-distributed into a uniform mass with the elements thereof held in suspension in the water in interlacing or felting position.

- of, while suspended in water. \Vithout the said chemical-treatment,'the gums or pectose material in the bast would hold the bundles of filaments cemented together and they would not open up or come apart when suspended in water. Moreover, said gums must be removed-or most thereofto prevent the presence of fermentable material in the final product. The raw, or uncooked shire, is of such a hard and stubborn nature that it will notlend itself to interlacing or felting purposes, until it is first softened up bysuch cooking. Shive, in its said raw or natural state, is, when dry, of less specific gravity than water and will float on the top of the same. The bast fiber, Whether raw or cooked will stand in suspension.in the water. The shive, after it has been cooked, as above described, will also stand in suspension in the water. Hence, whether the shive remains adherent to the bust, as most of it does, or is loose therefrom, as some of it will be, as thercooked stock comes into the water and after it has been properly manipulated therein, the whole thereofwill remain submerged or,. in other words all 7 the fibrous elements will stand insus ension in the water; and, hence,.by the proper careful manipulation of these fibrous elements so suspended in the Water, they can be brought into the uniform distribution required with the elements standing in the interlacing or felting relations, as above set 1 forth.

' From the foregoing, itwilll'be seen that the successful manipulation of the stock in' the water is "verydependent upon-the preliminary cookingthereof in theproper chemical solution for the proper length of time. It must, of course,'be' obvious "that unless the said uniform rearrangement and re-distribution of the saidfibrous elements can be made while the said elements remain suspended in the water to get the same into interlacingor felting relations in respect to each other, no product of uniform texture or even approximately uniform texture could be produced. After the said fibrous elements have been brought to the desired uniform distribution and remain suspended in the water in interlacing or felting relation, the next step of the process is to remove this uniformly distributed mass of fibrous elements from the water in such a Way as to complete the felting action. doneby any suitable gathering device raised through the water from below the suspended mass of fibrous elements and which gathering device is adapted tocatch and hold on its face the felting fibrous elements while permitting the water to escape through the felting fibrous mass. An ordinary screen of the proper mesh may be used for the purpose when'done by 'hand, or an under running apron, properly con structed, andwhich emerges from the water,

may be used if so desired. The downward flowage of the water through the felting fibrous mass on the face of the screen, or other gathering device, carries more or less of the finer fibers into intertangling relations with the coarser fibers and with each other, thereby further perfecting thefelting action as the screen or gathering device emerges from the water. The hand manipulation of the fibrous elements suspended in the water. continues while the gathering device is being lifted through'the water but no. longer and there is no shaking off the gathering device after it emerges from, or while it is within the Water.

The final step of the process is to compress and dry the felted material into a self sustaining sheet, and this may be done in any suitable way. 1

The finished sheet can be of any desired thickness, according to the amount of the cooked stock which, after being properly manipulated in water to get the fibrous elements properly suspended therein, as above described, is removed at one time or on any given section of the gathering device as it emerges from the water. It is the custom and practice to make the sheets from half an inch to an inch and one-half in thickness, varying according'to the usage intended.

This can be After the felted material has been- -properly compressed, andthoroughly dried, it 18,

of course, obvious that all the. tubular ultimate fibers of the bast and of the shire, and

that all the interstices between the felted fibrous elements, will contain dead air en- .caged therein; or,.in other words, air held therein in such a way that no circulation .readily applied to the great diversity of structures wherein heat insulation is desired. It is especially well adapted for use as a lining for refrigerators, cold storage compartments, house sheathing, roof and floor under-linings and, generally, wherever a good heat insulator is needed. It has gone into the most extensive use on refrigerator cars. Inasmuch as the fermentable gums were removed by the cooking and the chemical solution, this flax felt will stand'moisture and heat without fermentation. However, for the best heat insulation, it must be kept dry. It is also worthy of note that it is a slow burner; it will burn, but does not readily do so.

The above described process for producing the above identified long-fiber flax felt may, of course, be carried out with the aid of to be so obvious that illustration of such apparatus is not needed. Digesters, suitable for use in eifectingthe cooking of the flax straw or tow in a suitable chemical solution, are old and well known in this art. The only additional essentials, for carrying out the process by hand, is a suitable-vat containing water in which the cooked stock can be manipulated to get: the fibrous elements uniformly distributed in interlacing or felting relation, while held suspended therein, and a suitable gathering device, such as a screen or its equivalent, for removing said suspended stock thereby from the water to complete the felting action; and suitable compressing and drying means to compact and dry the felted material into the finished sheet.

Although, up to the present time, I have never been able to carry out the second step of the process, above set forth, to-wit, the

re-distribution and re-arrangement of the cooked stock in water, required to get the fibrous elements lmiformly distributed and suspended therein in proper 'felting relations, without more or less hand manipula= tion, I have been able to greatly reduce the amount of handmanipulation required by the use of suitable mechanism, such as that disclosed in my prior Patent 1,023,473, of date, April'lfi, 1912, entitled Flax felt machine The mechanism disclosed in that a machine will tear apart the chunks or masses of cooked stock and separate the same up into smaller portions in the water, but some further hand manipulation is required to get the fibrous elements uniformly distributed and suspended in the water in interlacing or felting relation above the removing a ron or gathering device of that machine. hat machine also discloses suitable mechanism for compressing and drying the felted material into a felted sheet.

It should, perhaps, be noted that the water in the felting vat should be kept changing, or have a fresh water inlet and a suitable outflow, especially if reliance is to be placed upon the manipulation in the water in said vat to wash out the chemical liquor from the cooked stock. If desired, however, the cooked stock may be washed after it is dumped out from the digester to remove the liquor therefrom before the cooked material is put in the felting vat, and, in that event, the changing of the water in the felting vat need no); be so frequently made.

\Vhat I claim is: i

The process of producing'from flax straw or tow self sustaining sheets of long-fiber flax felt, suitable for heat insulating purposes, which process consists in first, cooking the flax straw or tow in an alkaline or equivalent chemical solution to soften the fibers and remove fermentable gums therefrom; secondly, in manipulating all of said cooked stock in water to get thefibrous elements uniformly distributed into interlacing or felting relations in respect to each other, while held in suspension in the water; thirdly, in the removal of this suspended uniform mass of fibrous elements from the water by a suitable gathering device adapted to catch and hold on its face the felting fibrous elements while permitting 4 JAMES E. LAPiPEN.

Witnesses:

G. W. W. HARDEN, A. J. Han-1s. 

